Given the global demand to reduce the use of fossil fuels and to reduce the associated production of the greenhouse gas, carbon dioxide (CO2), many new innovations and ideas have already emerged from the automotive industry to date, that minimize the fuel consumption of conventional internal combustion engines. However, to simultaneously meet the growing demand for more comfort and safety in automobiles, there must be an increase in auxiliary equipment. To supply the required energy to the extra components, mechanical power must be drawn from the internal combustion engine. The auxiliary units such as generator, air compressor, water pump and hydraulic steering pump, usually have a belt drive system for power. Among these known belts is the timing belt which is a part of an internal combustion engine that synchronizes the rotation of the crankshaft and the camshaft (or camshafts, if more than one are available) so that the engine valves open and close at the proper times during each cylinder intake and exhaust strokes. A timing belt is a belt that usually features teeth on the inside surface.
To make sure the belt can transmit power to the individual components in any situation, a defined pre-tensioning force must act on the belt. However, the friction caused by this mechanical belt drive leads to excess fuel consumption.
A belt tensioning device is disclosed in DE 101 18 277 A1 which includes a swinging lever mounted on a pivotal axis. A pre-tensioned spring acts on the lever. Spring tension is controlled by an electric motor with reverse motion prevention. The motor is controlled by an operational parameter associated with a stored engine characteristic diagram. However, such belt tensioner does not allow to adjust the belt tensioning in a flexible way, according to the engine operating conditions.
Therefore a need exists for a belt tensioner, which is designed to minimize the above inconveniences.